The present invention relates an copy board for a reproducing camera (hereinafter referred to merely as an "copy board", when applicable). More particularly, the invention relates to an copy board including mask members, which are moved in conformance with a photographing reduction setting, and an original guide member, which is moved in synchronization with the movement of the mask members.
It is often difficult to correctly position an original on the surface of an copy board. Particularly, when a light-transmitting original such as an X-ray is to be copied using a back lighting source, it is necessary to use a mask to block light around the borders of the original. Therefore, in this case, both the original and the mask must be carefully set in place. Heretofore, in such a case, first the original was set in place and then mask members made of a metal or an opaque plastic were manually placed around the original. This conventional method is of course slow.
Moreover, when a reproducing camera is used, sometimes it is desired for a copied picture to have a dimensional reference. Heretofore, a scale was manually placed alongside the original. This method is also of low efficiency.
Furthermore, the conventional copy board suffers from a problem in that the mask members were movably provided below the diffusion board of the copy board, and the mask members were made of a metal plate having both sides painted black, or they were made of a black plastic plate. Therefore, when the masked area is changed, the amount of absorption of light is changed, and the brightness of parts which are not masked (light-transmitting parts) is changed.
This will become more apparent from the graph of FIG. 4. That is, FIG. 4 indicates the fact that, as the original size is decreased from A to C, the overall brightness is decreased. If this phenomenon occurs in a reproducing camera, then the exposure will be incorrect, and accordingly the resultant image will be poor in quality. If the phenomenon occurs with an observing device such as a light table, the brightness of the light source must be adjusted to take into account the size of a original under observation. This is troublesome for the operator.